Gabusectin derivatives, processes for preparing them and their use

ABSTRACT

The present invention relates to a compound of formula (I)  
                 
 
     wherein the R, R 2 , R 3 , R 4 , R 5 , X, X 2 , X 3 , X 4  and X 5  are as defined herein, which are formed by the microorganism ST 003236 (DSM 14476) during fermentation, to a process for preparing and derivatizing the compound, to a pharmaceutical which comprises the compound and to a method for the treatment or prophylaxis of an infectious disease caused by bacteria comprising administering a pharmaceutically effective amount of the compound.

FIELD OF THE INVENTION

[0001] The invention relates to novel antibiotic compounds produced froma strain ST 003236 (DSM 14476). The invention also relates to theirphysiologically tolerated salts, stereoisomers, tautomers, derivatives,in particular ester derivatives, and obvious chemical equivalents, suchas ethers. The compounds of the invention are not only very activeagainst bacteria but are also well tolerated. In particular, as comparedwith the compounds in the prior art, the compounds according to theinvention contain an additional methyl group in the naphthyl moiety ofthe compounds of the invention.

BACKGROUND OF THE INVENTION

[0002] A large number of antibiotics are used therapeutically fortreating infectious diseases of bacterial origin. However, the pathogensare becoming increasingly resistant to the pharmaceuticals employed.Even what are termed multiresistant pathogens, which have becomeresistant not only to individual antibiotic groups, such as β-lactamantibiotics, glycopeptides or macrolides, but also carry severalresistances simultaneously, pose a great threat. There are evenpathogens that have become resistant to all the commercially availableantibiotics. Infectious diseases that are caused by these pathogens canno longer be treated. Therefore, there is a great need for novelantibiotics that can be used against resistant pathogens. Whilethousands of antibiotics have been described in the literature, most ofthem are too toxic to be used as pharmaceuticals.

[0003] A relatively large number of antibiotics having a tetramic acidbasic structure have already been described. Tetramic acid, i.e.2,4-pyrrolidinedione, is the parent compound for a variety of naturalproducts which are formed by some microorganisms and marineinvertebrates.

[0004] harzianic acid, an antibiotic which possesses very littleactivity, was described in 1994 (R. Sawa et al., J. Antibiotics, 47,731-732, 1994);

[0005] Natural tetramic acid derivatives that were published up until1994 are described in a review by B. J. L. Royles (Chem. Rev. 95, pages1981-2001, 1995). Further natural tetramic acid derivatives, some ofwhich possess antibacterial properties, have been described since 1995:

[0006] reutericyclin (A. Höltzel et al., Angew. Chem. 112, 2886-2888,2000) possesses slight antibacterial activity;

[0007] equisetin and phomasetin (S. S. Singh et al., Tetrahedron Lett.39, 2243-2246, 1998) are isomeric inhibitors of HIV-1 integrase;

[0008] cryptocin (J. Y. Li et al., Org. Lett. 2, 767-770, 2000) is anantimycotic compound; vancoresmycin (N. V. S. Ramakrishna et al., Int.Patent Publication No. WO 0028064), an antibiotic;

[0009] coniosetin (L. Vertesy et al., German patent application No. DE10060810.8), a potent antibiotic composed of a tetramic acid moiety anda naphthyl moiety.

[0010] The aforesaid compounds do not contain an additional methyl groupin the naphthyl moiety thereof, and such alters their polarity, theirchemical structure or their antimicrobial activity or other physicalproperties.

SUMMARY OF THE INVENTION

[0011] The invention accordingly relates to the compounds which areformed by the strain ST 003236 (DSM 14476) and to their physiologicallytolerated salts, stereoisomers, tautomers, derivatives, in particularester derivatives, and obvious chemical equivalents, such as ethers.

[0012] The invention also relates to a compound of formula (I)

[0013] wherein

[0014] R, R₂ and R₃ are each, independently,

[0015] H, or

[0016] C₁-C₆-alkyl, C₂-C₆-alkenyl or C₂-C₆-alkynyl, wherein the alkyl,alkenyl and alkynyl are straight-chain or branched and are optionallysubstituted, once or twice, by:

[0017] —OH,

[0018] ═O,

[0019] —O—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0020] —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0021] -aryl,

[0022] —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0023] —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0024] —NH₂ or

[0025] halogen,

[0026] wherein the alkyl, alkenyl and aryl portions of —O—C₁-C₆-alkyl,—O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and —NH—C₂-C₆-alkenyl can befurther substituted by —CN, -amide or -oxime functions;

[0027] R₄ is C₁-C₆-alkyl or C₂-C₆-alkenyl, wherein the alkyl and alkenylcan be straight-chain or branched and are optionally substituted once ortwice by:

[0028] —OH,

[0029] —O—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0030] —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0031] -aryl,

[0032] —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0033] —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0034] —NH₂ or

[0035] halogen,

[0036] wherein the alkyl, alkenyl and aryl portions of —O—C₁-C₆-alkyl,—O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and —NH—C₂-C₆-alkenyl can befurther substituted by —CN, -amide or -oxime functions;

[0037] R₅ is H or methyl; and

[0038] X, X₂, X₃, X₄ and X₅, are each independently O, NH,N—C₁-C₆-alkyl, N—C₂-C₆-alkenyl, N—C₂-C₆-alkynyl, N-acyl, N-aryl, N—O—Ror S,

[0039] or a stereoisomeric form or a tautomeric form of the compound offormula (I) or a mixture of the previously mentioned forms in any ratio,or a physiologically tolerated salt of the compound of formula (I) or ofa stereoisomeric form or of a tautomeric form of the compound of formula(I).

DETAILED DESCRIPTION OF THE INVENTION

[0040] Definitions of Terms

[0041] As used above, and throughout the description of the invention,the following terms, unless otherwise indicated, shall be understood tohave the following meanings.

[0042] C₁-C₆-alkyl is a straight-chain or branched alkyl having from 1to 6 C atoms, preferably having from 1 to 4 C atoms, e.g., methyl,ethyl, i-propyl, tert-butyl and hexyl.

[0043] C₂-C₆-alkenyl is a straight-chain or branched alkenyl having from2 to 6 C atoms, and is unsaturated once, twice or three times, e.g.,allyl, crotyl, 1-propenyl, penta-1,3-dienyl and pentenyl.

[0044] C₂-C₆-alkynyl is a straight-chain or branched alkynyl having from2 to 6 C atoms, and is unsaturated once or twice, e.g. propynyl, butynyland pentynyl.

[0045] Aryl is phenyl, benzyl or 1- or 2-naphthyl, which can also beadditionally substituted, for example by halogen, such as chlorine,bromine or fluorine, alkyl having 1-4 C atoms, preferably methyl,hydroxyl, alkoxy having 1-4 C atoms, such as methoxy, ortrifluoromethyl.

[0046] Acyl is an aliphatic-C(O)— or aromatic-C(O)— radical.Aliphatic-C(O)— has 1-7, preferably 1-4, C atoms, such as formyl,acetyl, propionyl, butyryl, hexanoyl, acryloyl, crotonoyl, orpropioloyl, which can be still further substituted, for example byhalogen, such as chlorine, bromine or fluorine, amino, or alkylaminohaving 1-4 C atoms, preferably (methyl or ethyl)amino groups.Aromatic-C(O)— can, for example, be benzoyl or naphthoyl that can alsobe additionally substituted, for example by halogen, such as chlorine,bromine or fluorine, by alkyl having 1-4 C atoms, preferably methyl,hydroxyl, amino, alkylamino having 1-4 C atoms, such as ethylamino, oralkoxy groups having 1-7, preferably 1-4, C atoms, in particularmethoxy.

[0047] Patient includes both human and other mammals.

[0048] Pharmaceutically effective amount is meant to describe an amountof compound or compounds according to the present invention effective inproducing the desired therapeutic effect.

[0049] Particular or Preferred Embodiments

[0050] The invention preferably relates to the compound of formula (I),wherein

[0051] R is H, or

[0052] C₁-C₆-alkyl, C₂-C₆-alkenyl or C₂-C₆-alkynyl, wherein the alkyl,alkenyl and alkynyl are straight-chain or branched and are optionallysubstituted once or twice by:

[0053] —OH,

[0054] ═O,

[0055] —O—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0056] —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0057] -aryl,

[0058] —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,

[0059] —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched,

[0060] —NH₂ or

[0061] halogen,

[0062] wherein the alkyl, alkenyl and aryl portions of —O—C₁-C₆-alkyl,—O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and —NH—C₂-C₆-alkenyl can befurther substituted by —CN, -amide or -oxime functions;

[0063] R₂ is H,

[0064] R₃ is CH₃,

[0065] R₄ is —CH═CH—CH₃

[0066] R₅ is CH₃, and

[0067] X, X₂, X₃, X₄ and X₅ are O.

[0068] Particularly preferably, the invention relates to the compound offormula (I), wherein

[0069] R is H,

[0070] R₂ is H or CH₃,

[0071] R₃ is CH₃,

[0072] R₄ is —CH═CH—CH₃,

[0073] R₅ is CH₃, and

[0074] X, X₂, X₃, X₄ and X₅ are O.

[0075] Tautomeric forms of the compound (I) are, for example, a compoundof formula (II)

[0076] wherein the substituents R, R₂, R₃, R₄, R₅, X, X₂, X₃, X₄ and X₅are defined as above, where tautomeric forms of the compounds of formula(I) result, for example, from the hydrogen-bonded tetramic acidstructural moiety,

[0077] and are converted into each other in solution in dependence onparameters such as pH and solvent polarity.

[0078] Unless otherwise indicated, chiral centers in the compounds offormulae (I) and (II) can be present in the R configuration or in the Sconfiguration. The invention relates both to the optically purecompounds and to stereoisomeric mixtures, such as enantiomeric mixturesand diasteromeric mixtures, in any ratio.

[0079] Of the compounds of formulae (I) and (II) according to theinvention, preference is given to those compounds wherein thesubstituted hydrogenated naphthyl moiety therein has the configurationof formula (III):

[0080] The invention furthermore relates to a compound of formula (IV),

[0081] to a compound of formula (V),

[0082] to a compound of formula (VI),

[0083] to a compound of formula (VII),

[0084] or to a stereoisomeric form or a tautomeric form of the compoundof formula (IV), (V), (VI) or (VII) or to a mixture of the respectivepreviously mentioned forms in any ratio, or to a physiologicallytolerated salt of the compound of formula (IV), (V), (VI) or (VII) or ofa stereoisomeric form or of a tautomeric form of the compound of formula(IV), (V), (VI) or (VII).

[0085] The invention furthermore relates to obvious chemical equivalentsof the compounds of formulae (I) to (VII). Obvious chemical equivalentsof the compounds according to the invention are compounds that possessthe same activity as the compounds according to the invention andexhibit a trivial chemical difference or which are converted, under mildconditions, into the compounds according to the invention. Saidequivalents include, for example, esters, azomethines (Schiff's bases),ketals, oximes, hydrogenation products, reduction products, complexes oraddition compounds of or with the compounds according to the invention.

[0086] For example, an activated acid, for example acid chlorides orother acid derivatives, can be reacted with the hydroxyl group of thecompound of the formula (I), or of one or more double bonds and/orcarbonyl groups of the compound of the formula (I) can be reduced with areducing agent, with double bonds being reduced, for example, usingH₂/Pd and carbonyl groups being reduced, for example, using NaBH₄. Theabovementioned methods for derivatizing are described in text books suchas Jerry March, Advanced Organic Chemistry, John Wiley & Sons, 4^(th)Edition, 1992. In order to carry out reactions selectively, it can beadvantageous to introduce suitable protecting groups, in a manner knownper se, prior to the reaction. The protecting groups are eliminatedafter the reaction and the reaction product is subsequently purified.

[0087] The invention furthermore relates to gabusectin, a compound thathas the empirical formula C₂₆H₃₇NO₅, as demonstrated by ESI and FAB massspectroscopy, and which is characterized by the ¹H NMR and ¹³C NMR datagiven in table 2, or to a stereoisomeric form or a tautomeric form ofthe compound gabusectin, or to a mixture of the respective previouslymentioned forms in any ratio, or to a physiologically tolerated salt ofthe compound gabusectin or of a stereoisomeric form or of a tautomericform of the compound gabusectin.

[0088] The invention furthermore relates to gabusectin methyl ester, acompound of the empirical formula C₂₇H₃₉NO₅, demonstrated by ESI and FABmass spectroscopy, and characterized by the ¹H NMR and ¹³C NMR datagiven in table 3, or to a stereoisomeric form or a tautomeric form ofthe compound gabusectin methyl ester, or to a mixture of the respectivepreviously mentioned forms in any ratio, or to a physiologicallytolerated salt of the compound gabusectin methyl ester or of astereoisomeric form or a tautomeric form of the compound gabusectinmethyl ester.

[0089] The invention furthermore relates to the compound of formula (I)that can be obtained by fermenting ST 003236 (DSM 14476), or a variantand/or mutants of ST 003236 (DSM 14476), in a culture medium until thecompound of formula (I) accumulates in the culture broth, then isolatingthe compound of formula (I) and, where desired, converting it into apharmacologically tolerated salt.

[0090] The invention also relates to a compound of the empirical formulaC₂₆H₃₇NO₅ (Gabusectin) that can be obtained by fermenting ST 003236 (DSM14476), or a variant and/or mutant of ST 003236 (DSM 14476) in a culturemedium until the compound gabusectin accumulates in the culture broth,subsequently isolating the compound Gabusectin and, where desired,converting it into a pharmacologically tolerated salt.

[0091] The invention additionally relates to a process for preparing thecompound of formula (I) that comprises culturing the microorganism ST003236 (DSM 14476), or a variant and/or mutant of ST 003236 (DSM 14476),in an aqueous nutrient medium, isolating and purifying a compound offormula (I) and, where desired, converting it into an obvious chemicalequivalent or a pharmacologically tolerated salt.

[0092] The invention furthermore relates to a process for preparing thecompound of formula (I), wherein R is C₁-C₆-alkyl-, C₂-C₆-alkenyl- orC₂-C₆-alkynyl, R₂ is H, R₃ is CH₃, R₄ is —CH═CH—CH₃, R₅ is CH₃, and X,X₂, X₃, X₄ and X₅ are O, which comprises esterifying the compound offormula (IV) with a C₁-C₆-alkyl-, C₂-C₆-alkenyl- orC₂-C₆-alkynyl-alcohol derivative, or with a C₁-C₆-alkyl-, C₂-C₆-alkenyl-or C₂-C₆-alkynyl-alkylating agent, to give the compound of formula (I),wherein R is C₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl, whereinC₁-C₆-alkyl, C₂-C₆-alkenyl and C₂-C₆-alkynyl are straight-chain orbranched and can optionally be substituted, once or twice, by asubstituent selected from a group consisting of —OH, ═O, —O—C₁-C₆-alkyl,wherein the alkyl is straight-chain or branched, —O—C₂-C₆-alkenyl,wherein the alkenyl is straight-chain or branched, -aryl,—NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain or branched,—NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain or branched,—NH₂ or halogen, wherein the alkyl, alkenyl and aryl portionsof-O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, —O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and —N H—C₂-C₆-alkenyl can be further substituted by —CN,-amide or -oxime functions, and R₂ is H, R₃ is CH₃, R₄ is —CH═CH—CH₃, R₅is CH₃, and X, X₂, X₃, X₄ and X₅ are O, preferably using aC₁-C₆-alkyl-alkylating agent, particularly preferably using aC₁-alkylating agent.

[0093] The C₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl-alcoholderivative is straight-chain or branched and can optionally besubstituted once or twice, by a substituent selected from the groupconsisting of —OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl isstraight-chain or branched, —O—C₂-C₆-alkenyl, wherein the alkenyl isstraight-chain or branched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl isstraight-chain or branched, —NH—C₂-C₆-alkenyl, wherein the alkenyl isstraight-chain or branched, —NH₂ or halogen, wherein the alkyl, alkenyland aryl portions of-O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, —O—C₂-C₆-alkenyl,-aryl, —NH—C₁-C₆-alkyl, and —NH—C₂-C₆-alkenyl can be further substitutedby —CN, -amide or -oxime functions. The alcohol derivatives, forexample, include methanol, ethanol, n-propanol, isopropanol, n-butanol,sec-butanol, tert-butanol and n-hexanol, 2-buten-1-ol (crotyl alcohol),1-propen-3-ol (allyl alcohol), 1,3-pentadien-5-ol, 1,4-pentadien-3-oland 2-penten-1-ol, 1-penten-4-ol (allylmethylcarbinol), 1-penten-3-ol(ethylvinylcarbinol), 2-propyn-1-ol (propargyl alcohol), 1-butyn-3-ol,2-butyn-1-ol, 3-butyn-1-ol, 1-pentyn-3-ol, 2-pentyn-1-ol, 3-pentyn-1-oland 4-pentyn-1-ol; preferably methanol.

[0094] The C₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl-alkylatingagent is straight-chain or branched and can optionally be substitutedonce or twice, by a substituent selected from the group consisting of—OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, —NH₂ or halogen, wherein the alkyl, alkenyl and aryl portionsof —O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, —O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and —N H—C₂-C₆-alkenyl can be further substituted by —CN,-amide or -oxime functions. The alkylating agents, for example, includediazomethane derivatives as C₁-alkylating agents, for exampletrimethylsilyidiazomethane.

[0095] Methods/conditions for esterifying are described, for example, inJerry March, Advanced Organic Chemistry, John Wiley & Sons, 4^(th)Edition, 1992.

[0096] The strain ST 003236 has been deposited in the Deutsche Sammlungvon Microorganismen und Zellkulturen [German collection ofmicroorganisms and cell cultures] GmbH (DSMZ), Mascheroder Weg 1B, 38124Braunschweig, Germany, in accordance with the rules of the BudapestTreaty, under the following number DSM 14476.

[0097] Said process comprises culturing ST 003236 (DSM 14476), itsmutants or variants, under aerobic conditions in a culture mediumcontaining one or more carbon and nitrogen sources, inorganic salts and,optionally, trace elements. The carbon source is a carbohydrate or sugaralcohol, such as glucose, lactose, saccharose or D-mannit, or acarbohydrate containing natural product, such as a malt extract or ayeast extract that is capable of being assimilated. The nitrogen sourceis for example an amino acid, a peptide, i.e., a synthetically orbiosynthetically produced peptide, a protein, meat extract, yeastextract, ground seeds, distillation residues from alcohol production,ground meat, an ammonium salt or a nitrate salt. The protein is, e.g.,casein, peptone or tryptone. The meat extract, yeast extract and groundseeds are for example from corn, wheat, bean, soy or cotton source. Theinorganic salt is, e.g., a chloride, a carbonate, a sulfate or aphosphate of an alkali or alkaline, iron, or zinc. The trace element is,e.g., a chloride, a carbonate, a sulfate or a phosphate of a cobalt ormanganese salt.

[0098] The course of the fermentation, and the formation of theantibiotics according to the invention, can be monitored using methodsknown to a skilled person, for example by testing the biologicalactivity in bioassays or by means of chromatographic methods such asthin layer chromatography (TLC) or high performance liquidchromatography (HPLC).

[0099] A mutant is a microorganism wherein the one or more genes in thegenome has/have been modified, with the gene or genes that is/areresponsible for the ability of the organism to produce the compoundaccording to the invention remaining functional and inheritable.

[0100] Such mutants can be generated, in a manner known per se, byphysical means, for example irradiation, such as with ultraviolet raysor X-rays, or using chemical mutagens, such as ethyl methanesulfonate(EMS); 2-hydroxy-4-methoxy-benzo-phenone (MOB) orN-methyl-N′-nitro-N-nitrosoguanidine (MNNG), or as described by Brock etal. in “Biology of Microorganisms”, Prentice Hall, pages 238-247 (1984).

[0101] A variant is a phenotype of the microorganism. Microorganismshave the ability to adapt to their environment and therefore demonstratepronounced physiological flexibility. In phenotypic adaptation, all thecells in the microorganism are involved, with the nature of the changenot being genetically conditioned and being reversible under alteredcircumstances (H. Stolp, Microbial ecology: organism, habitats,activities. Cambridge University Press, Cambridge, GB, page 180, 1988).

[0102] Screening for mutants and variants which produce the antibioticaccording to the invention can be carried out by determining thebiological activity of the active compound which has accumulated in theculture broth, for example by determining its antibacterial effect, orby detecting compounds, which are known to be antibacterially active, inthe fermentation broth using HPLC or LC-MS methods, for example.

[0103] The compound gabusectin is found both in the mycelium and in theculture filtrate. It is therefore expedient to separate the fermentationsolution into the culture filtrate and the mycelium by means offiltration and to dry these fractions separately. The dried culturefiltrate and the dried mycelium are expediently extracted separatelywith an organic solvent, for example methanol or 2-propanol.

[0104] While the extraction can be carried out over a wide pH range, itis expedient to carry it out in a neutral or weakly acidic medium,preferably between pH 3 and pH 7. The extract can, for example, beconcentrated and dried in vacuo.

[0105] One method of isolating the antibiotic according to the inventionis in accordance with the polarity separation principle, in a mannerknown per se.

[0106] Another method of purification is chromatography on adsorptionresins, for example on Diaion® HP-20 (Mitsubishi Casei Corp., Tokyo), onAmberlite® XAD 7 (Rohm and Haas, USA), on Amberchrom® CG, (Toso Haas,Philadelphia, USA) or on similar materials. A large number ofreverse-phase supports, such as RP₈ and RP₁₈, as have become well known,for example, within the context of high pressure liquid chromatography(HPLC), are also suitable.

[0107] Another possibility for purifying the compound according to theinvention is that of using what are termed normal-phase chromatographysupports, such as silica gel or Al₂O₃, or other supports, in a mannerknown per se.

[0108] An alternative isolation method is that of using molecularsieves, such as Fractogel® TSK HW-40 (Merck, Germany) and others, in amanner known per se. In addition to this, it is also possible to isolatethe gabusectin by crystallization from enriched material. Organicsolvents and their mixtures, either anhydrous or containing added water,are, for example, suitable for this purpose. An additional method forisolating and purifying the antibiotics according to the invention isthat of using anion exchangers, preferably in a pH range of from 4 to10, and cation exchangers, preferably in a pH range of from 2 to 5. Theuse of buffer solutions to which quantities of organic solvents havebeen added is particularly suitable for this purpose. Gabusectin, thechemical derivatives thereof, and the obvious chemical equivalentsthereof, can be converted into the corresponding pharmacologicallytolerated salts using methods known to a skilled person.

[0109] Pharmacologically tolerated salts of the compounds according tothe invention are understood as being both inorganic and organic salts,as are described in Remington's Pharmaceutical Sciences (17th edition,page 1418 [1985]). Suitable salts are, in particular, alkali metalsalts, ammonium salts, alkaline earth metal salts, salts withphysiologically tolerated amines and salts with inorganic or organicacids, such as HCl, HBr, H₂SO₄, maleic acid, and fumaric acid.

[0110] It has been found, surprisingly, that the compounds of formula(I) according to the invention exhibit antibacterial effects and aretherefore suitable for the treatment of diseases which are caused bybacterial infection. Table 1 summarizes the minimum inhibitoryconcentrations (MICs) of gabusectin, by way of example. TABLE 1 In-vitroantibacterial activity of the compound gabusectin in a serial dilutiontest. Bacterium (strain) MIC values (μg/ml) S. aureus (SG511)  5 S.aureus (Exp54146) 20 S. pyogenes (A561) 20 E. faecium (M78L) 40

[0111] Gabusectin is well-tolerated at and above its effectiveconcentration.

[0112] The present invention, therefore, also relates to a method forthe treatment or prophylaxis of an infectious disease caused bybacteria, in a patient in need thereof, comprising administering to thepatient a pharmaceutically effective amount of a compound according tothe invention.

[0113] The present invention, furthermore, relates to a pharmaceuticalcomposition comprising at least one compound according to the invention,and one or more physiological auxiliary substances.

[0114] The pharmaceuticals according to the invention can be usedenterally (orally), parenterally (intramuscularly or intravenously),rectally or locally (topically). They can be administered in the form ofsolutions, powders (tablets and capsules, including microcapsules),ointments (creams or gels), or suppositories. Suitable auxiliarysubstances for such formulations are the pharmaceutically customaryliquid or solid fillers and extenders, solvents, emulsifiers, glidants,taste corrigents, dyes and/or buffering substances. 0.1-1 000,preferably 0.2-100, mg/kg of body weight is/are administered as anexpedient dose. The doses are expediently administered in dosage unitsthat contain at least the effective daily quantity of the compoundsaccording to the invention, for example 30-3 000, preferably 50-1000,mg.

EXAMPLES

[0115] The following examples are intended to be used for clarifying theinvention without in any way restricting its scope.

Example 1 Preparing a Glycerol Culture of ST 003236 (DSM 14476)

[0116] 30 ml of nutrient solution (malt extract, 2.0%, yeast extract,0.2%, glucose, 1.0%, (NH₄)₂HPO₄, 0.05%, pH 6.0) were inoculated with thestrain ST 003236 (DSM 14476) in a sterile 100 ml Erlenmeyer flask andincubated for 6 days, at 25° C. and 140 rpm, on a rotating shaker. 1.5ml of this culture were then diluted with 2.5 ml of 80% glycerol andstored at −135° C.

Example 2 Preparing a Preliminary Culture of ST 003236 (DSM 14476) in anErlenmeyer Flask

[0117] 100 ml of nutrient solution (malt extract, 2.0%, yeast extract,0.2%, glucose, 1.0%, (NH₄)₂HPO₄, 0.05%, pH 6.0) were inoculated with anampoule of the strain ST 003236 (DSM 14476) in a sterile 300 mlErlenmeyer flask and incubated for 6 days at 25° C. and 140 rpm. 2 ml ofthis preliminary culture were subsequently inoculated for preparing themain cultures.

Example 3 Preparing a Liquid Main Culture of ST 003236 (DSM 14476)

[0118] A sterile 300 ml Erlenmeyer flask containing 100 ml of thefollowing nutrient solution: potato dextrose, 2.4%, yeast extract, 0.2%,was inoculated with a culture grown on a sloping tube (same nutrientsolution but containing 2% agar) or with 2 ml of a preliminary culture(see example 2) and incubated, at 140 rpm and 25° C., on a shaker. Themaximum production of one or more compounds of the formula (I) accordingto the invention was reached after approx. 144 hours. A 96 hour-oldsubmerged culture from the same nutrient solution (inoculation quantity,approx. 10%) was adequate for inoculating fermenters of from 10 to 2001in volume. The conditions for these fermenters were:

[0119] Temperature: 25° C.

[0120] Stirrer speed: 200 rpm

[0121] Aeration: 15 l min⁻¹.

[0122] It was possible to suppress foam formation by repeatedly addingethanolic polyol solution. The production maximum was achieved afterapprox. 96 to 144 hours.

Example 4 Isolating the Compound Gabusectin

[0123] 3 l of culture solution, obtained as described in example 3, werefiltered and the culture filtrate and the mycelium were freeze-driedseparately. The dried culture filtrate was extracted with 3 liters ofmethanol. The clear liquid phase was concentrated down to 200 ml invacuo and filtered. This methanol solution was mixed with water in aratio of 9:1 in an HPLC high pressure gradient unit and loaded onto a300 ml-capacity column filled with the adsorption resin MCI Gel® CHP20P(Mitsubishi Casei Corp., Tokyo). Column dimensions: width×height: 5cm×15 cm. The column was eluted with a solvent gradient of water to 100%methanol and the outflow from the column (50 ml/minute) was collected infractions of in each case 25 ml in volume. The gabusectin-containingfractions 65 to 75, which were checked by HPLC analyses, were collectedand concentrated in vacuo and freeze-dried (0.23 g).

Example 5 Purifying Gabusectin by High Pressure Liquid Chromatography(HPLC)

[0124] Column: Purospher ® STAR RP-18 e 3 μm, 30-2, (Merck, Germany)Mobile phase buffer A: 5% acetonitrile + 0.1% ammonium acetate, Mobilephase buffer B: 95% acetonitrile + 0.1% ammonium acetate, Gradient: 15min Flow rate: 0.25 ml per minute

[0125] Detection by UV absorption at 210 nm.

[0126] Gabusectin was found to have a retention time of 6.5 min.

Example 6 Final Purification of Gabusectin

[0127] The enriched antibiotic gabusectin (0.23 g), obtained asdescribed in example 4, was fractionated on a LUNA® 10 μm C 18(2) HPLCcolumn (Phenomenex, USA) (width×height=2.1 cm×25 cm) by the gradientmethod using from 5% to 95% acetonitrile in 0.05% trifluoroacetic acid.Flow rate: 25 ml/min. Fraction size: 25 ml. Fraction 48, that wasexamined by analytical HPLC (see example 5) was freeze-dried. It yielded50 mg of gabusectin at 98% purity.

Example 7 Characterizing Gabusectin

[0128] The physicochemical and spectroscopic properties of theantibiotic according to the invention can be summarized as follows:

[0129] Appearance:

[0130] Colorless to pale yellow substance that is soluble inmedium-polar and polar organic solvents but not particularly soluble inwater. Stable in neutral and mildly acidic medium but unstable instrongly acidic and strongly alkali solution. Empirical formula:C₂₆H₃₇NO₅ Molecular weight: 443.59 ¹H NMR and ¹³C NMR: see table 2 UVmaxima: 236 nm and 294 nm

[0131] Determining the Molar Peak:

[0132] The mass of 443 is assigned to the sought-after molecule on thebasis of the following findings: ESI⁺ spectrum and FAB⁺ spectra exhibitpeaks at 444 amu (M+H)⁺. ESI⁻ spectrum exhibits a peak at 442 amu(M−H)⁻. High resolution of the quasi molecule ion: FAB⁺ 444.27424(M+H)⁺. 443.59 was calculated for the empirical formula C₂₆H₃₇NO₅. TABLE2 ¹H- and ¹³C-chemical shifts of gabusectin in CDCl₃ at 275 K.

¹³C δ ¹H δ Position (ppm) (ppm) HMBC correlations (¹³C-¹H) 1 49.01 —H3-Me(w), H1-Me, H2(w), H10, 14-OH 1-Me 20.77 1.24 s — 2 45.69 3.36H3-Me, H9′, H1-Me, H10, H4, H12(s), H11(w) 3 132.86 — H11(w), H2,H3-Me(s), H6′(w) 3-Me 23.43 1.69 s H4 4 130.04 5.06 H2, H10, H3-Me(s),H6′, H5-Me(s) 5 37.61 — H6′, H7-Me(w), H5-Me(s), H10, H4(s) 5-Me 31.910.70 H3-Me, H6′, H10(w) 6 51.62 1.36, H3-Me(w), H9′, H7-Me, H5-Me, H4(w)0.92 7 29.46 1.26 H6(w), H6′, H9(w), H7-Me(s), H5-Me(w) 7-Me 22.41 0.81d — 8 34.97 1.65, H9(w), H9′(w), H6(w), H6′, H7-Me(s) 0.87 9 25.52 1.84,H10 1.29 10 42.17 2.66 dd H9′, H1-Me, H5-Me, H2(w), H4 11 132.25 5.31H12, H2(w), H13(s) 12 128.95 5.44 H11, H2, H13(s) 13 17.90 1.69 H12, H1114 203.37 — 14-OH, H2, H10, H1-Me 14-OH — 17.73 — 15 98.81 — 14-OH 16177.05 — 14-OH, H18(s), H17-Me(s) 17-Me 27.20 3.02 s — 18 64.27 3.76 ddH17-Me, H20, H20′ 19 190.36 — H18, H20(w), H20′ 20 23.27 2.32, H21, H182.08 21 27.44 2.30, H20, H20′, H18 2.30 22 178.18 — H20, H21 22-COOH —7.1 br —

Example 8 Inhibitory Effect of Gabusectin in the Agar Diffusion Test

[0133] Agar plates containing 2 ml of Staphylococcus aureus inoculum in200 ml of agar solution were prepared. Gabusectin was applied, in a 10mM solution, to 6 mm-diameter paper disks, which were then laid on theagar plate. The inoculated Staphylococcus plates were incubated at 37°C. for 16 hours. Inhibition halos having the following diameters (mm)were then observed: Quantity Inhibition halo size (mm) 10 μL  8 20 μL 1440 μL 17

Example 9 Methylation, and Subsequent Purification of the GabusectinMethyl Ester

[0134] 20 mg of the antibiotic gabusectin (0.045 mmol), obtained asdescribed in example 6, were dissolved in 5 ml of MeOH, after whichtrimethylsilyldiazomethane was added in a 6-fold molar excess. Thereaction mixture was left to stand at room temperature for 60 min andthen concentrated to dryness. The resulting mixture was fractionatedchromatographically on a LUNA® 5 μm C 18(2) HPLC column (Phenomenex,USA) (width×height=1 cm×25 cm) by the gradient method using from 5% to95% acetonitrile in 0.05% trifluoroacetic acid. Flow rate: 6.5 ml/min.Fraction size: 6.5 ml.

[0135] Fraction 61, which was examined by analytical HPLC (see example5), was freeze-dried. It yielded 7.4 mg of gabusectin methyl ester at97% purity.

Example 10 Characterizing Gabusectin Methyl Ester

[0136] The physicochemical and spectroscopic properties of theantibiotic according to the invention can be summarized as follows:

[0137] Appearance:

[0138] Colorless to pale-yellow substance that is soluble inmedium-polar and polar organic solvents but not particularly soluble inwater. Stable in neutral and mildly acidic medium but unstable instrongly acidic and strongly alkaline solution. Empirical formula:C₂₇H₃₉NO₅ Molecular weight: 457.62 ¹H NMR and ¹³NMR: see table 3 UVmaxima: 236 nm and 294 nm

[0139] Determination of the Molar Peak:

[0140] The mass of 457.6 is assigned to the sought-after molecule on thebasis of the following findings: ESI⁺ spectrum and FAB⁺ spectra exhibitpeaks at 457 amu (M+H)⁺. ESI⁻ spectrum exhibits a peak at 458.5 amu(M−H)⁻. TABLE 3 ¹H and ¹³C chemical shifts of gabusectin methyl ester inCDCl₃ at 275 K

¹³C δ ¹H δ Position (ppm) (ppm) HMBC correlations (¹³C- ¹H) 1 48.89 —H3-Me(w), H1-Me, H10(w) 1-Me 20.83 1.24 — 2 45.70 3.36 H3-Me, H1-Me,H9′, H10(w), H12, H4 3 132.86 — H3-Me 3-Me 23.44 1.68 H4 4 130.08 5.05H3-Me, H6′, H5-Me, H10(w) 5 37.63 — H6′, H5-Me, H10(w), H4(w) 5-Me 31.910.70 H10(w), H6′, H3-Me(w) 6 51.65 1-35, H9′, H7-Me, H5-Me, H4(w) 0.92 729.48 1.25 H6′, H7-Me 7-Me 22.42 0.80 — 8 35.00 1.64, H6′, H7-Me(s) 0.889 25.55 1.83, H10 1.30 10 42.17 2.67 H1-Me, H5-Me, H9′, H4(w) 11 132.355.30 H12, H13 12 128.87 5.43 H11, H13 13 17.90 1.69 H12, H11 14 202.86 —H1-Me 14-OH — 17.75 — 15 98.91 — — 16 177.06 — H17-Me 17-Me 27.13 3.02 —18 64.49 3.71 H20, H20′, H21, H17-Me 19 190.33 — H18, H20′ 20 23.522.29, H21 2.11 21 27.42 2.23, — 2.23 22 173.05 — 22-OMe, H20, H20′, H2122-OMe 51.93 3.66 —

Example 11 Inhibitory Effect of the Gabusectin Methyl Ester in the AgarDiffusion Test

[0141] Agar plates containing 2 ml of Staphylococcus aureus inoculum in200 ml of agar solution were prepared. Gabusectin methyl ester isapplied, in a 10 mM solution, to 6 mm-diameter paper disks, which arethen laid on the agar plate. The inoculated Staphylococcus plates wereincubated at 37° C. for 16 hours. Inhibition halos having the followingdiameters (mm) were then observed. Quantity Inhibition halo size (mm) 10μL 0 20 μL 7 40 μL 8

[0142] The present invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof.

We claim:
 1. A compound of formula (I)

wherein R, R₂ and R₃ are each, independently, H, or C₁-C₆-alkyl,C₂-C₆-alkenyl or C₂-C₆-alkynyl, wherein the alkyl, alkenyl and alkynylare straight-chain or branched and are optionally substituted, once ortwice, by: —OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl is straight-chainor branched, —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, —NH₂ or halogen, wherein the alkyl, alkenyl and aryl portionsof —O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and—NH—C₂-C₆-alkenyl can be further substituted by —CN, -amide or -oximefunctions; R₄ is C₁-C₆-alkyl or C₂-C₆-alkenyl, wherein the alkyl andalkenyl can be straight-chain or branched and are optionally substitutedonce or twice by: —OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl isstraight-chain or branched, —O—C₂-C₆-alkenyl, wherein the alkenyl isstraight-chain or branched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl isstraight-chain or branched, —NH—C₂-C₆-alkenyl, wherein the alkenyl isstraight-chain or branched, —NH₂ or halogen, wherein the alkyl, alkenyland aryl portions of —O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, -aryl,—NH—C₁-C₆-alkyl, and —NH—C₂-C₆-alkenyl can be further substituted by—CN, -amide or -oxime functions; R₅ is H or methyl; and X, X₂, X₃, X₄and X₅, are each independently O, NH, N—C₁-C₆-alkyl, N—C₂-C₆-alkenyl,N—C₂-C₆-alkynyl, N-acyl, N-aryl, N—O—R or S, or a stereoisomeric form ora tautomeric form of the compound of formula (I) or a mixture of thepreviously mentioned forms in any ratio, or a physiologically toleratedsalt of the compound of formula (I) or of a stereoisomeric form or of atautomeric form of a compound of formula (I).
 2. A compound according toclaim 1, wherein R is H, or C₁-C₆-alkyl, C₂-C₆-alkenyl or C₂-C₆-alkynyl,wherein the C₁-C₆-alkyl, C₂-C₆-alkenyl and C₂-C₆-alkynyl arestraight-chain or branched and are optionally substituted once or twiceby: —OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, —NH₂ or halogen, wherein the alkyl, alkenyl and aryl portionsof —O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and—NH—C₂-C₆-alkenyl can be further substituted by —CN, -amide or -oximefunctions; R₂ is H, R₃ is CH₃, R₄ is —CH═CH—CH₃, R₅ is CH₃, and X, X₂,X₃, X₄ and X₅ are O.
 3. A compound according to claim 1, wherein R is H,R₂ is H or CH₃, R₃ is CH₃, R₄ is —CH═CH—CH₃, R₅ is CH₃, and X, X₂, X₃,X₄ and X₅ are O.
 4. A compound according to claim 1 of formula (IV)

or a stereoisomeric form or a tautomeric form of a compound of formula(IV) or a mixture of the respective previously mentioned forms in anyratio, or a physiologically tolerated salt of a compound of formula (IV)or of a stereoisomeric form or of a tautomeric form of a compound offormula (IV).
 5. A compound according to claim 1 of formula (V)

or a stereoisomeric form or a tautomeric form of a compound of formula(V) or a mixture of the respective previously mentioned forms in anyratio, or a physiologically tolerated salt of a compound of formula (V)or of a stereoisomeric form or of a tautomeric form of a compound offormula (V).
 6. A compound according to claim 1 of formula (VI)

or a stereoisomeric form or a tautomeric form of a compound of formula(VI) or a mixture of the respective previously mentioned forms in anyratio, or a physiologically tolerated salt of a compound of formula (VI)or of a stereoisomeric form or of a tautomeric form of a compound offormula (VI).
 7. A compound according to claim 1 of formula (VII)

or a stereoisomeric form or a tautomeric form of a compound of formula(VII) or a mixture of the respective previously mentioned forms in anyratio, or a physiologically tolerated salt of a compound of formula(VII) or of a stereoisomeric form or of a tautomeric form of a compoundof formula (VII).
 8. Gabusectin of empirical formula C₂₆H₃₇NO₅,demonstrated by ESI and FAB mass spectroscopy, and characterized by the¹H NMR data δ (CDCl₃, 275K)=0.70, 0.81, 0.87, 0.92, 1.24, 1.26, 1.29,1.36, 1.65, 1.69, 1.84, 2.08, 2.30, 2.32, 2.66, 3.02, 3.36, 3.76, 5.06,5.31, 5.44, 7.1, 17.73, and the ¹³C NMR data δ (CDCl₃, 275K)=17.90,20.77, 22.41, 23.27, 23.43, 25.52, 27.20, 27.44, 29.46, 31.91, 34.97,37.61, 42.17, 45.69, 49.01, 51.62, 64.27, 98.81, 128.95, 130.04, 132.25,132.86, 177.05, 178.18, 190.36, 203.37, or a stereoisomeric form or atautomeric form of the compound gabusectin or a mixture of therespective previously mentioned forms in any ratio, or a physiologicallytolerated salt of the compound gabusectin or of a stereoisomeric form orof a tautomeric form of the compound gabusectin.
 9. Gabusectin methylester of empirical formula C₂₇H₃₉NO₅, demonstrated by ESI and FAB massspectroscopy, and characterized by the ¹H NMR data δ (CDCl₃, 275K)=0.70,0.80, 0.88, 0.92, 1.24, 1.25, 1.30, 1.35, 1.64, 1.68, 1.69, 1.83, 2.11,2.23, 2.29, 2.67, 3.02, 3.36, 3.66, 3.71, 5.05, 5.30, 5.43, 17.75 andthe ¹³C NMR data δ (CDCl₃, 275K)=17.90, 20.83, 22.42, 23.44, 23.52,25.55, 27.13, 27.42, 29.48, 31.91, 35.00, 37.63, 42.17, 45.70, 48.89,51.65, 51.93, 64.49, 98.91, 128.87, 130.08, 132.35, 132.86, 173.05,177.06, 190.33, 202.86, or a stereoisomeric form or a tautomeric form ofthe compound gabusectin methyl ester or a mixture of the respectivepreviously mentioned forms in any ratio, or a physiologically toleratedsalt of the compound gabusectin methyl ester or of a stereoisomeric formor of a tautomeric form of the compound gabusectin methyl ester.
 10. Acompound of formula (I) as claimed in claim 1 obtained by fermenting ST003236 (DSM 14476), or a variant and/or mutant of ST 003236 (DSM 14476)in a culture medium until the compound of formula (I) accumulates in theculture broth, subsequently isolating the compound of formula (I) and,where desired, converting it into a pharmacologically tolerated salt.11. Gabusectin compound of empirical formula C₂₆H₃₇NO₅ (gabusectin)obtained by fermenting ST 003236 (DSM 14476) or a variant and/or mutantof ST 003236 (DSM 14476), in a culture medium until the compoundgabusectin accumulates in the culture broth, subsequently isolating thecompound gabusectin and, where desired, converting it into apharmacologically tolerated salt.
 12. A process for preparing a compoundof formula (I) as claimed in claim 1, which comprises culturing themicroorganism ST 003236 (DSM 14476), or a variant and/or mutant of ST003236 in an aqueous nutrient medium, isolating and purifying thecompound of formula (I), and, where desired, converting it into anobvious chemical equivalent or a pharmacologically tolerated salt. 13.The process as claimed in claim 12, wherein the microorganism ST 003236(DSM 14476) or a mutant and/or variant of ST 003236 is fermented, underaerobic conditions, in a culture medium containing one or more carbonand nitrogen sources, and inorganic salts, and optionally, traceelements.
 14. The process as claimed in claim 12 or 13, wherein thefermentation under aerobic conditions is carried out at a temperaturebetween 20 and 35° C. and at a pH of between 4 and
 10. 15. A process forpreparing a compound of formula (I) as claimed in claim 1, wherein R isC₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl, R₂ is H, R₃ is CH₃, R₄ is—CH═CH—CH₃, R₅ is CH₃, and X, X₂, X₃, X₄ and X₅ are O, that comprisesesterifying a compound of formula (IV) as claimed in claim 4, with aC₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl-alcohol derivative or witha C₁-C₆-alkyl-, C₂-C₆-alkenyl- or C₂-C₆-alkynyl-alkylating agent to givethe compound of formula (I), wherein the alkyl, alkenyl and alkynyl arestraight-chain or branched and can be optionally substituted once ortwice by: —OH, ═O, —O—C₁-C₆-alkyl, wherein the alkyl is straight-chainor branched, —O—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, -aryl, —NH—C₁-C₆-alkyl, wherein the alkyl is straight-chain orbranched, —NH—C₂-C₆-alkenyl, wherein the alkenyl is straight-chain orbranched, —NH₂ or halogen, wherein the alkyl, alkenyl and aryl portionsof —O—C₁-C₆-alkyl, —O—C₂-C₆-alkenyl, -aryl, —NH—C₁-C₆-alkyl, and—NH—C₂-C₆-alkenyl can be further substituted by —CN, -amide or -oximefunctions.
 16. The process for preparing the compound of formula (I) asclaimed in claim 15, wherein the esterification is carried out using aC₁-alkylating agent.
 17. A method for the treatment or prophylaxis of aninfectious disease caused by bacteria, in a patient in need thereof,comprising administering to the patient a pharmaceutically effectiveamount of a compound as claimed in any one of claims 1, 8-9 or
 11. 18. Apharmaceutical composition comprising at least one compound as claimedin any one of claims 1, 8-9 or 11 and one or more physiologicallysuitable auxiliary substances.
 19. The microorganism ST003236 (DSM14476).